Hyaluronidase activity in lysosomes of bone tissue

Uptake and in vitro anticancer activity of oleic acid delivered in nanocapsules stabilized by amphiphilic derivatives of hyaluronic acid and chitosan

The nanoemulsion-based delivery systems have gained particular attention due to effective encapsulation and protection of hydrophobic active compounds. However, several features like limited stability, cellular uptake or release of payloads still need to be addressed. We investigated the uptake of the nanocapsules based on the amphiphilic derivative of hyaluronate with oleic acid cores (oil-in-water nanoemulsion) and their anticancer activity in vitro. The core-shell nanocapsules exhibiting long term stability in dispersion showed an enhanced uptake by cancer cells and effectively killed them only if composed of hyaluronate-based shells and oleic acid cores - the anionic chitosan-based shells and/or corn oil cores were used for control experiments. We concluded that the nanocapsules stabilized by the amphiphilic derivative of hyaluronic acid may serve as very stable and efficient delivery systems for oil-soluble compounds without necessity of application of low molecular weight (co)surfactants. The in vitro studies indicated anticancer activity of such delivered oleic acid and crucial role of hyaluronate shell of the nanocapsules in its efficient delivery and enzyme-triggered disintegration inside cells. Corn oil was shown as a nutrient that can serve as an inert vehicle in the studied nanoemulsion that exhibit application potential in food, dietary supplement industry and medicine.

Plasma hyaluronidase activity in mucolipidoses II and III: marked differences from other lysosomal enzymes

A nearly pathognomonic finding of the lysosomal storage disorders mucolipidoses II and III is the marked increase of plasma lysosomal enzyme activities. The genetic lesion in ML II and III causes defective function of the enzyme UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase. Defective function of this enzyme results in deficient phosphorylation of lysosomal enzyme asparagine-linked oligosaccharides and a consequent misrouting of many newly synthesized lysosomal enzymes. These enzymes are secreted from cells instead of being targeted to lysosomes, with resultant marked elevations of multiple lysosomal enzyme activities in plasma. We report here that plasma hyaluronidase activity, an endoglycosidase of presumably lysosomal origin, is not increased in the plasma from individuals with mucolipidoses II and III, unlike most lysosomal enzymes. Our data suggest the possibility that hyaluronidase is not targeted to lysosomes by a lysosomal enzyme phosphosmannosyl recognition mechanism. Alternatively, hyaluronidase activity may not be present in the cell type(s) responsible for the lysosomal enzyme hypersecretion in mucolipidoses II and III which, along with its deficiency in fibroblasts and leukocytes, would constitute an unusual tissue distribution of activity for a soluble lysosomal enzyme.

Size-dependent hyaluronate degradation by cultured cells

Hyaluronate degradation was examined in cultures of vascular wall cells (bovine aortic endothelial cells, rat aortic smooth muscle cells) and in nonvascular cells (chick embryo fibroblasts). The three cell types examined all produced hyaluronidase activity in culture which had a strict acidic pH requirement for activity. This suggested that the enzyme was active only within an acidic intracellular compartment and therefore that hyaluronate degradation occurred at an intracellular site. This was supported by the observation that the presence of hyaluronidase activity alone was not sufficient to ensure degradation of extracellular hyaluronate. Rather, the key limiting factor in this process appeared to be hyaluronate internalization, and this was found to be hyaluronate size-dependent and to a degree, cell-specific. The relationship of these results to morphogenesis and tissue remodeling is discussed.

Processing and lysosomal localization of a glycoprotein whose secretion is transformation stimulated

The major excreted protein (MEP) of transformed mouse fibroblasts is a mannose 6-phosphate-containing glycoprotein whose synthesis and secretion are increased in malignantly transformed 3T3 cells and whose synthesis is increased by treatment of 3T3 cells with tumor promoters or growth factors. When pulse-labeled extracts from Kirsten virus-transformed NIH 3T3 (KNIH) cells were immunoprecipitated using an antibody against secreted MEP, one cellular protein was immunoprecipitated that had the same molecular weight and tryptic peptide map as the secreted protein. Pulse-chase labeling experiments showed that 50-60% of this 39,000-mol-wt form was secreted in transformed cells. Of the 40-50% remaining, approximately 5% was processed into two lower molecular weight forms (29,000 and 20,000) which are sequestered within the cell. Similar processing of these proteins was observed in the nontransformed parent NIH 3T3 (NIH) cells. However, in NIH cells, much less of the synthesized MEP was secreted. Measurements of steady-state levels of these three forms of cellular MEP by Western blot immunolocalization revealed approximately fourfold more MEP in KNIH cells than in NIH cells as well as differences in the relative distribution of MEP forms in transformed and nontransformed cells. Subcellular fractionation of KNIH cells on a Percoll gradient demonstrated a distribution of total MEP similar to that of several lysosomal enzymes. The light lysosomal/Golgi peak from these gradients contained both the precursor 39,000-mol-wt form of MEP and the 20,000-mol-wt form, whereas the heavy lysosomal peak was enriched in the 20,000-mol-wt form. The distribution of MEP forms was found to be similar in NIH cells except that the 29,000-mol-wt form was also seen to be enriched in the heavy lysosomal peak. This biochemical localization of MEP was confirmed by immunolocalization with light and electron microscopy. These data support the hypothesis that MEP is a lysosomal protein that is secreted by transformed cells.

Degradation of glycosaminoglycans by extracts of calf vitreous hyalocytes

The ability of extracts of calf vitreous hyalocytes to catalyze the degradation of glycosaminoglycans was studied by incubation with radioactively labeled substrates. The degradation of the polymeric substrates to lower molecular weight products was assayed by three methods: (1) paper chromatographic separation of low molecular weight, mobile digestion products from undigested, high molecular weight material which remains at or near the origin; (2) loss of the ability of the glycosaminoglycan to be precipitated by cetylpyridinium chloride; (3) gel chromatography to separate low molecular weight digestion products, which appear in the retarded volume, from undegraded, high molecular weight material, which is eluted in the void volume. The acidic pH optimum of the reaction suggests a lysosomal origin of the enzyme activity.

Identification of hyaluronidase activity in rabbit dental pulp

A hyaluronidase activity was demonstrated in rabbit dental pulp. The optimum pH of the enzyme was 3.8. The enzyme activity was enhanced by protamine and poly-L-lysine and was inhibited by iodoacetamide, ferric ion, and ferrous ion in decreasing order. The product of the enzyme reaction was identified as tetrasaccharide. From these results it was concluded that the enzyme exists in pulp tissue and is functioning for degradation of proteoglycans in situ.

Mucopolysaccharidase activity in traumatized human deciduous teeth undergoing accelerated resorption: isolation and characterization

Mucopolysaccharidase activity was observed in traumatized human decidous teeth. Histochemical analysis of the periodontal ligaments from these teeth revealed a loss of film substrate metachromasia during incubation, indicating enzyme activity. Routine histology of these ligaments showed the presence of an inflammatory infiltrate throughout this tissue. Biochemical analysis of the ligaments revealed a 10-fold increase of enzyme activity when incubation time was increased from 1 to 8 h. When compared to the enzyme activity measured during physiologic resorption, activity was increased. This suggests that the presence of an inflammatory infiltrate not observed in the tissues undergoing physiologic resorption may be responsible for the rapid resorption seen in traumatized deciduous teeth.

Cathepsin D: ultra-immunohistochemical localization in dentinogenesis

Cathepsin D was purified from rat liver using a new affinity chromatographic method, based on the coupling to the specific inhibitor pepstatin. This preparation was used for the production of specific antibodies from rabbit. The purified IgG fraction was conjugated to horseradish peroxidase in a two-step coupling procedure and used for electron microscopic immunohistochemistry of the odontoblast-predentine region of the rat incisor. Precipitates, indicating the presence of cathepsin D, were seen in the odontoblast, odontoblast process, and in the extracellular unmineralized matrix, the predentine. The observations are discussed in relation to proteoglycan degradation at the mineralization front simultaneous with crystal formation, and in relation to the function of lysosomal enzymes in the turnover of connective tissue.

Canine submandibular-gland hyaluronidase. Identification and subcellular distribution

1. Submandibular glands from four species of mammal have been shown to contain a hyaluronidase active at acid pH; glands from dog and cat had a much higher content of this enzyme than has been found in other sources. 2. Product formation from hyaluronate after 24hr. incubation was almost the same as with testicular hyaluronidase, indicating that the enzyme is an endo-poly-beta-hexosaminidase. 3. When submandibular-gland homogenates were fractionated by the scheme developed for liver by de Duve, Pressman, Gianetto, Wattiaux & Appelmans (1955), all the enzymes assayed, except cytochrome c oxidase, were found to occur partly in the soluble fraction and partly in the particulate fractions. Among the particular fractions, the highest specific activity was found in the heavy-mitochondrial fraction for cytochrome c oxidase, in the microsomal fraction for alkaline phosphatase and in the light-mitochondrial fraction for acid phosphatase, beta-N-acetylhexosaminidase and acid-active hyaluronidase. 4. Release of the enzyme activity from the sedimentable fractions occurred in 0.1% Triton X-100 or after high-speed homogenization. 5. Stimulation of dogs by pilocarpine was found to decrease the hyaluronidase content of the submandibular gland by 5% and to cause the occurrence of a corresponding amount of acid-active hyaluronidase in the submandibular saliva. 6. The results are discussed in relation to the subcellular localization of hyaluronidase.

Canine submandibular-gland hyaluronidase. Purification and properties

1. Methods for the purification of dog submandibular-gland hyaluronidase from sedimentable and non-sedimentable portions of a homogenate and from the whole homogenate are presented. The method consists of three main steps: removal of mucin by acid precipitation or gel filtration on Sephadex G-200, ammonium sulphate precipitation and CM-cellulose chromatography. By this method specific activities of up to 1.28 and 0.78mumoles of N-acetylglucosamine/min./mg. of protein were obtained for the purified freeze-dried non-sedimentable hyaluronidase and for the sedimentable hyaluronidase respectively. 2. A comparison of some of the properties of the non-sedimentable and the sedimentable hyaluronidase preparation indicated that there was little difference between the two and that they both resembled lysosomal hyaluronidase from rat liver.